1. Field of the Invention
The present invention relates to a multi-directional input apparatus which includes an operating member provided with a drive shaft and which outputs an electric signal in accordance with a tilting direction and a tilting angle of the drive shaft when the operating member is tilted. More particularly, the present invention relates to a multi-directional input apparatus including a swinging member which has a long hole through which the drive shaft is inserted and which is rotated when the drive shaft is tilted.
2. Description of the Related Art
In this type of multi-directional input apparatus, when the operating member supported such that the operating member is tiltable in multiple directions is tilted, an electric signal can be obtained which differs in accordance with the tilting direction and the tilting angle of the operating member. Therefore, the multi-directional input apparatus is suitable for use as, for example, an input apparatus in which functions of multiple control devices, such as an air conditioner, an audio device, and a navigation device, that are mounted on a vehicle are adjusted using a single operating member.
Japanese Unexamined Patent Application Publication No. 6-12137 discloses an example of such a multi-directional input apparatus. This multi-directional input apparatus includes a swinging member that is rotatably supported on a base and an operating member provided with a drive shaft that is inserted through a long hole formed in the swinging member. When the operating member is tilted in a direction that crosses an axial direction of the swinging member, the swinging member is rotated by the drive shaft and an electric signal corresponding to the rotation angle of the swinging member is output from a detector, such as a variable resistor. As in the structure of the related art disclosed in Japanese Unexamined Patent Application Publication No. 6-12137, a pair of swinging members having the above-described structure may be arranged such that the axial directions thereof extend perpendicular to each other, and the drive shaft of the operating member may be inserted through long holes formed in the swinging members. In such a case, the tilting direction and the tilting angle of the operating member tilted in an arbitrary direction can be detected from output values obtained by a pair of detectors which correspond to the swinging members. In the structure of the related art, rolling elements, such as bearings, are attached to the drive shaft of the operating member so that the rolling elements roll along the inner walls of the long holes in the swinging members when the operating member is tilted. The rolling elements are provided to prevent rattling when the operating member is repeatedly tilted and contact surfaces between the drive shaft of the operating member and the inner walls of the long holes are worn.
Japanese Unexamined Patent Application Publication No. 2005-332156 discloses another example of a multi-directional input apparatus. This multi-directional input apparatus includes a swinging member and a swinging holder which is supported such that the swinging holder is rotatable along a plane perpendicular to an axial direction of the swinging member. A drive shaft of an operating member is rotatably supported by the swinging holder, and the axial direction of the drive shaft is substantially parallel to the axial direction of the swinging member. Also in this structure, the tilting direction and the tilting angle of the operating member tilted in an arbitrary direction can be detected from output values obtained by a pair of detectors which correspond to the swinging member and the swinging holder.
In the structure of the related art disclosed in Japanese Unexamined Patent Application Publication No. 6-12137, the rolling elements, such as bearings, are attached to the drive shaft of the operating member to prevent wear. Therefore, even when the operating member is repeatedly tilted, a possibility that rattling will occur between the drive shaft of the operating member and the inner walls of the long holes in the swinging members is low. However, slight clearances must be provided between the rolling elements and the inner walls of the long holes so that the rolling elements attached to the drive shaft can be placed in the long holes. Therefore, in the case where, for example, the multi-directional input apparatus is mounted on a vehicle, there is a risk that the rolling elements will come into contact with the inner walls of the long holes due to vibration generated when the vehicle is driven. In such a case, abnormal sound called rattling noise will be generated. In addition, the structure of the related art in which the rolling elements, such as bearings, are attached to the drive shaft of the operating member is complex. Therefore, a high component cost and an assembly cost are incurred. As a result, the cost of the multi-directional input apparatus will be increased.
In the structure of the related art disclosed in Japanese Unexamined Patent Application Publication No. 2005-332156, the cost is not increased since no rolling element, such as bearing, is additionally provided. However, a clearance must be provided between the drive shaft of the operating member and the inner wall of a long hole formed in the swinging member so that the drive shaft can be placed in the long hole. The size of the clearance gradually increases when the operating member is repeatedly tilted. Therefore, in this structure, the operating member tends to generate noise, such as the rattling noise, in a vibrating environment if the apparatus is used for a long period of time.